In various image forming devices, toner images are formed on a photoreceptor and then transferred directly to receiving substrates. In other various systems and methods, toner images are transported to fuser rolls or belts and then fixed onto the receiving substrate by heat and pressure. Specifically, the fuser rolls and belts can be heated to melt and press the toner onto the substrates when the substrates pass through the rolls and belts. Various fuser roll systems include a heated fuser roller and a pressure roller to form a nip through which a receiving substrate can pass. The receiving substrate, before passing through the nip, contains previously deposited toner. The heated fuser roll in combination with the pressure roll acts to melt and press the previously deposited toner onto the receiving substrate. Various belt systems can also act to melt and press toner onto the receiving substrate. In both cases, the fusing of the toner particles generally takes place when the proper combination of heat, pressure, and contact time are provided.
The use of thermal energy for fusing toner images onto a substrate is well known in the art. Heat generation in conventional fusing systems can be accomplished by using heaters inside the fuser member, such as quartz rods or lamps located inside the fuser roll. Heat is transferred from the rods or lamps to the outer surface of the fuser roll. Other fusing systems use inductive heating of the fuser member layers such as the fuser roll and the fusing belt. In an inductive heating system, an electrical coil is disposed in close proximity to a heatable fuser member. Alternating current (AC) is sent through an electrical induction coil which generates a magnetic field, which induces eddy currents in the fuser member to heat the fuser member.
In conventional inductive heating fuser systems, metals such as nickel, copper, silver, aluminum, and the like are used as susceptor layers in the heatable fuser members. However, these metals require a high amount of current through the induction coil to heat to a target temperature. Further, high currents in the induction coil can lead to circuit losses and inefficiencies in the fuser system. Still further, optimal heat generation is not achieved with existing combinations of thicknesses and resistivities of the susceptor layers.
Thus, there is a need for an induction heating system with a susceptor layer comprising materials that will require lower currents in the induction coil to reach a target temperature, resulting in a smaller and more cost efficient power supply as well as a higher energy efficiency for the printing process. Further, there is a need for susceptor layers with the right thickness and resistivity combination for optimal heat generation. As such, circuit losses will be minimized throughout the components to lead to a more efficient induction heating system.